The full name of FEP is Fluorinated ethylene propylene, which is the best choice for welding all kinds of pipes because of its inherent temperature resistance, smoothness and low shrinkage temperature. The guide tube is usually composed of three layers, that is, the inner layer is PTFE (Tiferon) inner layer, the middle layer is made of stainless steel wire braid or spring coil structure, and the outer layer is Pebax material. At the same time, the distal end and the proximal end of different hardness materials welded to form a complete conduit. The FEP heat shrink tube produced by Soco Medical is basically used to fuse three layers of different materials into a suitable tube body. It is this "sandwich" structural design of inner lining + intermediate layer + outer layer + surface coating that creates excellent universality of the microcatheter.